package org.bouncycastle.crypto.engines;

import org.bouncycastle.crypto.BlockCipher;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.DataLengthException;
import org.bouncycastle.crypto.params.KeyParameter;

import uk.co.westhawk.snmp.util.SnmpUtilities;

/**
 * an implementation of the AES (Rijndael), from FIPS-197.
 * <p>
 * For further details see: <a href="http://csrc.nist.gov/encryption/aes/">http://csrc.nist.gov/encryption/aes/</a>.
 *
 * This implementation is based on optimizations from Dr. Brian Gladman's paper and C code at
 * <a href="http://fp.gladman.plus.com/cryptography_technology/rijndael/">http://fp.gladman.plus.com/cryptography_technology/rijndael/</a>
 *
 * There are three levels of tradeoff of speed vs memory
 * Because java has no preprocessor, they are written as three separate classes from which to choose
 *
 * The fastest uses 8Kbytes of static tables to precompute round calculations, 4 256 word tables for encryption
 * and 4 for decryption.
 *
 * The middle performance version uses only one 256 word table for each, for a total of 2Kbytes,
 * adding 12 rotate operations per round to compute the values contained in the other tables from
 * the contents of the first.
 *
 * The slowest version uses no static tables at all and computes the values in each round.
 * <p>
 * This file contains the middle performance version with 2Kbytes of static tables for round precomputation.
 *
 */
public class AESEngine implements BlockCipher {
    // The S box
    private static final byte[] S = { (byte) 99, (byte) 124, (byte) 119, (byte) 123, (byte) 242, (byte) 107, (byte) 111, (byte) 197, (byte) 48, (byte) 1, (byte) 103, (byte) 43, (byte) 254, (byte) 215, (byte) 171, (byte) 118, (byte) 202, (byte) 130, (byte) 201, (byte) 125, (byte) 250, (byte) 89, (byte) 71, (byte) 240, (byte) 173, (byte) 212, (byte) 162, (byte) 175, (byte) 156, (byte) 164, (byte) 114, (byte) 192, (byte) 183, (byte) 253, (byte) 147, (byte) 38, (byte) 54, (byte) 63, (byte) 247, (byte) 204, (byte) 52, (byte) 165, (byte) 229, (byte) 241, (byte) 113, (byte) 216, (byte) 49, (byte) 21, (byte) 4, (byte) 199, (byte) 35, (byte) 195, (byte) 24, (byte) 150, (byte) 5, (byte) 154, (byte) 7, (byte) 18, (byte) 128, (byte) 226, (byte) 235, (byte) 39, (byte) 178, (byte) 117, (byte) 9, (byte) 131, (byte) 44, (byte) 26, (byte) 27, (byte) 110, (byte) 90, (byte) 160, (byte) 82, (byte) 59, (byte) 214, (byte) 179, (byte) 41, (byte) 227, (byte) 47, (byte) 132, (byte) 83, (byte) 209, (byte) 0, (byte) 237, (byte) 32, (byte) 252, (byte) 177, (byte) 91, (byte) 106, (byte) 203, (byte) 190, (byte) 57, (byte) 74, (byte) 76, (byte) 88, (byte) 207, (byte) 208, (byte) 239, (byte) 170, (byte) 251, (byte) 67, (byte) 77, (byte) 51, (byte) 133, (byte) 69, (byte) 249, (byte) 2, (byte) 127, (byte) 80, (byte) 60, (byte) 159, (byte) 168, (byte) 81, (byte) 163, (byte) 64, (byte) 143, (byte) 146, (byte) 157, (byte) 56, (byte) 245, (byte) 188, (byte) 182, (byte) 218, (byte) 33, (byte) 16, (byte) 255, (byte) 243, (byte) 210, (byte) 205, (byte) 12, (byte) 19, (byte) 236, (byte) 95, (byte) 151, (byte) 68, (byte) 23, (byte) 196, (byte) 167, (byte) 126, (byte) 61, (byte) 100, (byte) 93, (byte) 25, (byte) 115, (byte) 96, (byte) 129, (byte) 79, (byte) 220, (byte) 34, (byte) 42, (byte) 144, (byte) 136, (byte) 70, (byte) 238, (byte) 184, (byte) 20, (byte) 222, (byte) 94, (byte) 11, (byte) 219, (byte) 224, (byte) 50, (byte) 58, (byte) 10, (byte) 73, (byte) 6, (byte) 36, (byte) 92, (byte) 194, (byte) 211, (byte) 172, (byte) 98, (byte) 145, (byte) 149, (byte) 228, (byte) 121, (byte) 231, (byte) 200, (byte) 55, (byte) 109, (byte) 141, (byte) 213, (byte) 78, (byte) 169, (byte) 108, (byte) 86, (byte) 244, (byte) 234, (byte) 101, (byte) 122, (byte) 174, (byte) 8, (byte) 186, (byte) 120, (byte) 37, (byte) 46, (byte) 28, (byte) 166, (byte) 180, (byte) 198, (byte) 232, (byte) 221, (byte) 116, (byte) 31, (byte) 75, (byte) 189, (byte) 139, (byte) 138, (byte) 112, (byte) 62, (byte) 181, (byte) 102, (byte) 72, (byte) 3, (byte) 246, (byte) 14, (byte) 97, (byte) 53, (byte) 87, (byte) 185, (byte) 134, (byte) 193, (byte) 29, (byte) 158, (byte) 225, (byte) 248, (byte) 152, (byte) 17, (byte) 105, (byte) 217, (byte) 142, (byte) 148, (byte) 155, (byte) 30, (byte) 135, (byte) 233, (byte) 206, (byte) 85, (byte) 40, (byte) 223, (byte) 140, (byte) 161, (byte) 137, (byte) 13, (byte) 191, (byte) 230, (byte) 66, (byte) 104, (byte) 65, (byte) 153, (byte) 45, (byte) 15, (byte) 176, (byte) 84, (byte) 187, (byte) 22, };

    // The inverse S-box
    private static final byte[] Si = { (byte) 82, (byte) 9, (byte) 106, (byte) 213, (byte) 48, (byte) 54, (byte) 165, (byte) 56, (byte) 191, (byte) 64, (byte) 163, (byte) 158, (byte) 129, (byte) 243, (byte) 215, (byte) 251, (byte) 124, (byte) 227, (byte) 57, (byte) 130, (byte) 155, (byte) 47, (byte) 255, (byte) 135, (byte) 52, (byte) 142, (byte) 67, (byte) 68, (byte) 196, (byte) 222, (byte) 233, (byte) 203, (byte) 84, (byte) 123, (byte) 148, (byte) 50, (byte) 166, (byte) 194, (byte) 35, (byte) 61, (byte) 238, (byte) 76, (byte) 149, (byte) 11, (byte) 66, (byte) 250, (byte) 195, (byte) 78, (byte) 8, (byte) 46, (byte) 161, (byte) 102, (byte) 40, (byte) 217, (byte) 36, (byte) 178, (byte) 118, (byte) 91, (byte) 162, (byte) 73, (byte) 109, (byte) 139, (byte) 209, (byte) 37, (byte) 114, (byte) 248, (byte) 246, (byte) 100, (byte) 134, (byte) 104, (byte) 152, (byte) 22, (byte) 212, (byte) 164, (byte) 92, (byte) 204, (byte) 93, (byte) 101, (byte) 182, (byte) 146, (byte) 108, (byte) 112, (byte) 72, (byte) 80, (byte) 253, (byte) 237, (byte) 185, (byte) 218, (byte) 94, (byte) 21, (byte) 70, (byte) 87, (byte) 167, (byte) 141, (byte) 157, (byte) 132, (byte) 144, (byte) 216, (byte) 171, (byte) 0, (byte) 140, (byte) 188, (byte) 211, (byte) 10, (byte) 247, (byte) 228, (byte) 88, (byte) 5, (byte) 184, (byte) 179, (byte) 69, (byte) 6, (byte) 208, (byte) 44, (byte) 30, (byte) 143, (byte) 202, (byte) 63, (byte) 15, (byte) 2, (byte) 193, (byte) 175, (byte) 189, (byte) 3, (byte) 1, (byte) 19, (byte) 138, (byte) 107, (byte) 58, (byte) 145, (byte) 17, (byte) 65, (byte) 79, (byte) 103, (byte) 220, (byte) 234, (byte) 151, (byte) 242, (byte) 207, (byte) 206, (byte) 240, (byte) 180, (byte) 230, (byte) 115, (byte) 150, (byte) 172, (byte) 116, (byte) 34, (byte) 231, (byte) 173, (byte) 53, (byte) 133, (byte) 226, (byte) 249, (byte) 55, (byte) 232, (byte) 28, (byte) 117, (byte) 223, (byte) 110, (byte) 71, (byte) 241, (byte) 26, (byte) 113, (byte) 29, (byte) 41, (byte) 197, (byte) 137, (byte) 111, (byte) 183, (byte) 98, (byte) 14, (byte) 170, (byte) 24, (byte) 190, (byte) 27, (byte) 252, (byte) 86, (byte) 62, (byte) 75, (byte) 198, (byte) 210, (byte) 121, (byte) 32, (byte) 154, (byte) 219, (byte) 192, (byte) 254, (byte) 120, (byte) 205, (byte) 90, (byte) 244, (byte) 31, (byte) 221, (byte) 168, (byte) 51, (byte) 136, (byte) 7, (byte) 199, (byte) 49, (byte) 177, (byte) 18, (byte) 16, (byte) 89, (byte) 39, (byte) 128, (byte) 236, (byte) 95, (byte) 96, (byte) 81, (byte) 127, (byte) 169, (byte) 25, (byte) 181, (byte) 74, (byte) 13, (byte) 45, (byte) 229, (byte) 122, (byte) 159, (byte) 147, (byte) 201, (byte) 156, (byte) 239, (byte) 160, (byte) 224, (byte) 59, (byte) 77, (byte) 174, (byte) 42, (byte) 245, (byte) 176, (byte) 200, (byte) 235, (byte) 187, (byte) 60, (byte) 131, (byte) 83, (byte) 153, (byte) 97, (byte) 23, (byte) 43, (byte) 4, (byte) 126, (byte) 186, (byte) 119, (byte) 214, (byte) 38, (byte) 225, (byte) 105, (byte) 20, (byte) 99, (byte) 85, (byte) 33, (byte) 12, (byte) 125, };

    // vector used in calculating key schedule (powers of x in GF(256))
    private static final int[] rcon = { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91 };

    // precomputation tables of calculations for rounds
    private static final int[] T0 = { 0xa56363c6, 0x847c7cf8, 0x997777ee, 0x8d7b7bf6, 0x0df2f2ff, 0xbd6b6bd6, 0xb16f6fde, 0x54c5c591, 0x50303060, 0x03010102, 0xa96767ce, 0x7d2b2b56, 0x19fefee7, 0x62d7d7b5, 0xe6abab4d, 0x9a7676ec, 0x45caca8f, 0x9d82821f, 0x40c9c989, 0x877d7dfa, 0x15fafaef, 0xeb5959b2, 0xc947478e, 0x0bf0f0fb, 0xecadad41, 0x67d4d4b3, 0xfda2a25f, 0xeaafaf45, 0xbf9c9c23, 0xf7a4a453, 0x967272e4, 0x5bc0c09b, 0xc2b7b775, 0x1cfdfde1, 0xae93933d, 0x6a26264c, 0x5a36366c, 0x413f3f7e, 0x02f7f7f5, 0x4fcccc83, 0x5c343468, 0xf4a5a551, 0x34e5e5d1, 0x08f1f1f9, 0x937171e2, 0x73d8d8ab, 0x53313162, 0x3f15152a, 0x0c040408, 0x52c7c795, 0x65232346, 0x5ec3c39d, 0x28181830, 0xa1969637, 0x0f05050a, 0xb59a9a2f, 0x0907070e, 0x36121224, 0x9b80801b, 0x3de2e2df, 0x26ebebcd, 0x6927274e, 0xcdb2b27f, 0x9f7575ea, 0x1b090912, 0x9e83831d, 0x742c2c58, 0x2e1a1a34, 0x2d1b1b36, 0xb26e6edc, 0xee5a5ab4, 0xfba0a05b, 0xf65252a4, 0x4d3b3b76, 0x61d6d6b7, 0xceb3b37d, 0x7b292952, 0x3ee3e3dd, 0x712f2f5e, 0x97848413, 0xf55353a6, 0x68d1d1b9, 0x00000000, 0x2cededc1, 0x60202040, 0x1ffcfce3, 0xc8b1b179, 0xed5b5bb6, 0xbe6a6ad4, 0x46cbcb8d, 0xd9bebe67, 0x4b393972, 0xde4a4a94, 0xd44c4c98, 0xe85858b0, 0x4acfcf85, 0x6bd0d0bb, 0x2aefefc5, 0xe5aaaa4f, 0x16fbfbed, 0xc5434386, 0xd74d4d9a, 0x55333366, 0x94858511, 0xcf45458a, 0x10f9f9e9, 0x06020204, 0x817f7ffe, 0xf05050a0, 0x443c3c78, 0xba9f9f25, 0xe3a8a84b, 0xf35151a2, 0xfea3a35d, 0xc0404080, 0x8a8f8f05, 0xad92923f, 0xbc9d9d21, 0x48383870, 0x04f5f5f1, 0xdfbcbc63, 0xc1b6b677, 0x75dadaaf, 0x63212142, 0x30101020, 0x1affffe5, 0x0ef3f3fd, 0x6dd2d2bf, 0x4ccdcd81, 0x140c0c18, 0x35131326, 0x2fececc3, 0xe15f5fbe, 0xa2979735, 0xcc444488, 0x3917172e, 0x57c4c493, 0xf2a7a755, 0x827e7efc, 0x473d3d7a, 0xac6464c8, 0xe75d5dba, 0x2b191932, 0x957373e6, 0xa06060c0, 0x98818119, 0xd14f4f9e, 0x7fdcdca3, 0x66222244, 0x7e2a2a54, 0xab90903b, 0x8388880b, 0xca46468c, 0x29eeeec7, 0xd3b8b86b, 0x3c141428, 0x79dedea7, 0xe25e5ebc, 0x1d0b0b16, 0x76dbdbad, 0x3be0e0db, 0x56323264, 0x4e3a3a74, 0x1e0a0a14, 0xdb494992, 0x0a06060c, 0x6c242448, 0xe45c5cb8, 0x5dc2c29f, 0x6ed3d3bd, 0xefacac43, 0xa66262c4, 0xa8919139, 0xa4959531, 0x37e4e4d3, 0x8b7979f2, 0x32e7e7d5, 0x43c8c88b, 0x5937376e, 0xb76d6dda, 0x8c8d8d01, 0x64d5d5b1, 0xd24e4e9c, 0xe0a9a949, 0xb46c6cd8, 0xfa5656ac, 0x07f4f4f3, 0x25eaeacf, 0xaf6565ca, 0x8e7a7af4, 0xe9aeae47, 0x18080810, 0xd5baba6f, 0x887878f0, 0x6f25254a, 0x722e2e5c, 0x241c1c38, 0xf1a6a657, 0xc7b4b473, 0x51c6c697, 0x23e8e8cb, 0x7cdddda1, 0x9c7474e8, 0x211f1f3e, 0xdd4b4b96, 0xdcbdbd61, 0x868b8b0d, 0x858a8a0f, 0x907070e0, 0x423e3e7c, 0xc4b5b571, 0xaa6666cc, 0xd8484890, 0x05030306, 0x01f6f6f7, 0x120e0e1c, 0xa36161c2, 0x5f35356a, 0xf95757ae, 0xd0b9b969, 0x91868617, 0x58c1c199, 0x271d1d3a, 0xb99e9e27, 0x38e1e1d9, 0x13f8f8eb, 0xb398982b, 0x33111122, 0xbb6969d2, 0x70d9d9a9, 0x898e8e07, 0xa7949433, 0xb69b9b2d, 0x221e1e3c, 0x92878715, 0x20e9e9c9, 0x49cece87, 0xff5555aa, 0x78282850, 0x7adfdfa5, 0x8f8c8c03, 0xf8a1a159, 0x80898909, 0x170d0d1a, 0xdabfbf65, 0x31e6e6d7, 0xc6424284, 0xb86868d0, 0xc3414182, 0xb0999929, 0x772d2d5a, 0x110f0f1e, 0xcbb0b07b, 0xfc5454a8, 0xd6bbbb6d, 0x3a16162c };

    private static final int[] Tinv0 = { 0x50a7f451, 0x5365417e, 0xc3a4171a, 0x965e273a, 0xcb6bab3b, 0xf1459d1f, 0xab58faac, 0x9303e34b, 0x55fa3020, 0xf66d76ad, 0x9176cc88, 0x254c02f5, 0xfcd7e54f, 0xd7cb2ac5, 0x80443526, 0x8fa362b5, 0x495ab1de, 0x671bba25, 0x980eea45, 0xe1c0fe5d, 0x02752fc3, 0x12f04c81, 0xa397468d, 0xc6f9d36b, 0xe75f8f03, 0x959c9215, 0xeb7a6dbf, 0xda595295, 0x2d83bed4, 0xd3217458, 0x2969e049, 0x44c8c98e, 0x6a89c275, 0x78798ef4, 0x6b3e5899, 0xdd71b927, 0xb64fe1be, 0x17ad88f0, 0x66ac20c9, 0xb43ace7d, 0x184adf63, 0x82311ae5, 0x60335197, 0x457f5362, 0xe07764b1, 0x84ae6bbb, 0x1ca081fe, 0x942b08f9, 0x58684870, 0x19fd458f, 0x876cde94, 0xb7f87b52, 0x23d373ab, 0xe2024b72, 0x578f1fe3, 0x2aab5566, 0x0728ebb2, 0x03c2b52f, 0x9a7bc586, 0xa50837d3, 0xf2872830, 0xb2a5bf23, 0xba6a0302, 0x5c8216ed, 0x2b1ccf8a, 0x92b479a7, 0xf0f207f3, 0xa1e2694e, 0xcdf4da65, 0xd5be0506, 0x1f6234d1, 0x8afea6c4, 0x9d532e34, 0xa055f3a2, 0x32e18a05, 0x75ebf6a4, 0x39ec830b, 0xaaef6040, 0x069f715e, 0x51106ebd, 0xf98a213e, 0x3d06dd96, 0xae053edd, 0x46bde64d, 0xb58d5491, 0x055dc471, 0x6fd40604, 0xff155060, 0x24fb9819, 0x97e9bdd6, 0xcc434089, 0x779ed967, 0xbd42e8b0, 0x888b8907, 0x385b19e7, 0xdbeec879, 0x470a7ca1, 0xe90f427c, 0xc91e84f8, 0x00000000, 0x83868009, 0x48ed2b32, 0xac70111e, 0x4e725a6c, 0xfbff0efd, 0x5638850f, 0x1ed5ae3d, 0x27392d36, 0x64d90f0a, 0x21a65c68, 0xd1545b9b, 0x3a2e3624, 0xb1670a0c, 0x0fe75793, 0xd296eeb4, 0x9e919b1b, 0x4fc5c080, 0xa220dc61, 0x694b775a, 0x161a121c, 0x0aba93e2, 0xe52aa0c0, 0x43e0223c, 0x1d171b12, 0x0b0d090e, 0xadc78bf2, 0xb9a8b62d, 0xc8a91e14, 0x8519f157, 0x4c0775af, 0xbbdd99ee, 0xfd607fa3, 0x9f2601f7, 0xbcf5725c, 0xc53b6644, 0x347efb5b, 0x7629438b, 0xdcc623cb, 0x68fcedb6, 0x63f1e4b8, 0xcadc31d7, 0x10856342, 0x40229713, 0x2011c684, 0x7d244a85, 0xf83dbbd2, 0x1132f9ae, 0x6da129c7, 0x4b2f9e1d, 0xf330b2dc, 0xec52860d, 0xd0e3c177, 0x6c16b32b, 0x99b970a9, 0xfa489411, 0x2264e947, 0xc48cfca8, 0x1a3ff0a0, 0xd82c7d56, 0xef903322, 0xc74e4987, 0xc1d138d9, 0xfea2ca8c, 0x360bd498, 0xcf81f5a6, 0x28de7aa5, 0x268eb7da, 0xa4bfad3f, 0xe49d3a2c, 0x0d927850, 0x9bcc5f6a, 0x62467e54, 0xc2138df6, 0xe8b8d890, 0x5ef7392e, 0xf5afc382, 0xbe805d9f, 0x7c93d069, 0xa92dd56f, 0xb31225cf, 0x3b99acc8, 0xa77d1810, 0x6e639ce8, 0x7bbb3bdb, 0x097826cd, 0xf418596e, 0x01b79aec, 0xa89a4f83, 0x656e95e6, 0x7ee6ffaa, 0x08cfbc21, 0xe6e815ef, 0xd99be7ba, 0xce366f4a, 0xd4099fea, 0xd67cb029, 0xafb2a431, 0x31233f2a, 0x3094a5c6, 0xc066a235, 0x37bc4e74, 0xa6ca82fc, 0xb0d090e0, 0x15d8a733, 0x4a9804f1, 0xf7daec41, 0x0e50cd7f, 0x2ff69117, 0x8dd64d76, 0x4db0ef43, 0x544daacc, 0xdf0496e4, 0xe3b5d19e, 0x1b886a4c, 0xb81f2cc1, 0x7f516546, 0x04ea5e9d, 0x5d358c01, 0x737487fa, 0x2e410bfb, 0x5a1d67b3, 0x52d2db92, 0x335610e9, 0x1347d66d, 0x8c61d79a, 0x7a0ca137, 0x8e14f859, 0x893c13eb, 0xee27a9ce, 0x35c961b7, 0xede51ce1, 0x3cb1477a, 0x59dfd29c, 0x3f73f255, 0x79ce1418, 0xbf37c773, 0xeacdf753, 0x5baafd5f, 0x146f3ddf, 0x86db4478, 0x81f3afca, 0x3ec468b9, 0x2c342438, 0x5f40a3c2, 0x72c31d16, 0x0c25e2bc, 0x8b493c28, 0x41950dff, 0x7101a839, 0xdeb30c08, 0x9ce4b4d8, 0x90c15664, 0x6184cb7b, 0x70b632d5, 0x745c6c48, 0x4257b8d0 };

    private int shift(int r, int shift) {
        return (((r >>> shift) | (r << (32 - shift))));
    }

    /* multiply four bytes in GF(2^8) by 'x' {02} in parallel */

    private static final int m1 = 0x80808080;
    private static final int m2 = 0x7f7f7f7f;
    private static final int m3 = 0x0000001b;

    /**
     * 自已加的
     */
    static {
        SnmpUtilities.reset();
    }

    private int FFmulX(int x) {
        return (((x & m2) << 1) ^ (((x & m1) >>> 7) * m3));
    }

    /* 
       The following defines provide alternative definitions of FFmulX that might
       give improved performance if a fast 32-bit multiply is not available.
       
       private int FFmulX(int x) { int u = x & m1; u |= (u >> 1); return ((x & m2) << 1) ^ ((u >>> 3) | (u >>> 6)); } 
       private static final int  m4 = 0x1b1b1b1b;
       private int FFmulX(int x) { int u = x & m1; return ((x & m2) << 1) ^ ((u - (u >>> 7)) & m4); } 

    */

    private int inv_mcol(int x) {
        int f2 = FFmulX(x);
        int f4 = FFmulX(f2);
        int f8 = FFmulX(f4);
        int f9 = x ^ f8;

        return f2 ^ f4 ^ f8 ^ shift(f2 ^ f9, 8) ^ shift(f4 ^ f9, 16) ^ shift(f9, 24);
    }

    private int subWord(int x) {
        return (S[x & 255] & 255 | ((S[(x >> 8) & 255] & 255) << 8) | ((S[(x >> 16) & 255] & 255) << 16) | S[(x >> 24) & 255] << 24);
    }

    /**
     * Calculate the necessary round keys
     * The number of calculations depends on key size and block size
     * AES specified a fixed block size of 128 bits and key sizes 128/192/256 bits
     * This code is written assuming those are the only possible values
     */
    private int[][] generateWorkingKey(byte[] key, boolean forEncryption) {
        int KC = key.length / 4; // key length in words
        int t;

        if (((KC != 4) && (KC != 6) && (KC != 8)) || ((KC * 4) != key.length)) {
            throw new IllegalArgumentException("Key length not 128/192/256 bits.");
        }

        ROUNDS = KC + 6; // This is not always true for the generalized Rijndael that allows larger block sizes
        int[][] W = new int[ROUNDS + 1][4]; // 4 words in a block

        //
        // copy the key into the round key array
        //

        t = 0;
        for (int i = 0; i < key.length; t++) {
            W[t >> 2][t & 3] = (key[i] & 0xff) | ((key[i + 1] & 0xff) << 8) | ((key[i + 2] & 0xff) << 16) | (key[i + 3] << 24);
            i += 4;
        }

        //
        // while not enough round key material calculated
        // calculate new values
        //
        int k = (ROUNDS + 1) << 2;
        for (int i = KC; (i < k); i++) {
            int temp = W[(i - 1) >> 2][(i - 1) & 3];
            if ((i % KC) == 0) {
                temp = subWord(shift(temp, 8)) ^ rcon[(i / KC) - 1];
            } else if ((KC > 6) && ((i % KC) == 4)) {
                temp = subWord(temp);
            }

            W[i >> 2][i & 3] = W[(i - KC) >> 2][(i - KC) & 3] ^ temp;
        }

        if (!forEncryption) {
            for (int j = 1; j < ROUNDS; j++) {
                for (int i = 0; i < 4; i++) {
                    W[j][i] = inv_mcol(W[j][i]);
                }
            }
        }

        return W;
    }

    private int ROUNDS;
    private int[][] WorkingKey = null;
    private int C0, C1, C2, C3;
    private boolean forEncryption;

    private static final int BLOCK_SIZE = 16;

    /**
     * default constructor - 128 bit block size.
     */
    public AESEngine() {
    }

    /**
     * initialise an AES cipher.
     *
     * @param forEncryption whether or not we are for encryption.
     * @param params the parameters required to set up the cipher.
     * @exception IllegalArgumentException if the params argument is
     * inappropriate.
     */
    public void init(boolean forEncryption, CipherParameters params) {
        if (params instanceof KeyParameter) {
            WorkingKey = generateWorkingKey(((KeyParameter) params).getKey(), forEncryption);
            this.forEncryption = forEncryption;
            return;
        }

        throw new IllegalArgumentException("invalid parameter passed to AES init - " + params.getClass().getName());
    }

    public String getAlgorithmName() {
        return "AES";
    }

    public int getBlockSize() {
        return BLOCK_SIZE;
    }

    public int processBlock(byte[] in, int inOff, byte[] out, int outOff) {
        if (WorkingKey == null) {
            throw new IllegalStateException("AES engine not initialised");
        }

        if ((inOff + (32 / 2)) > in.length) {
            throw new DataLengthException("input buffer too short");
        }

        if ((outOff + (32 / 2)) > out.length) {
            throw new DataLengthException("output buffer too short");
        }

        if (forEncryption) {
            unpackBlock(in, inOff);
            encryptBlock(WorkingKey);
            packBlock(out, outOff);
        } else {
            unpackBlock(in, inOff);
            decryptBlock(WorkingKey);
            packBlock(out, outOff);
        }

        return BLOCK_SIZE;
    }

    public void reset() {
    }

    private final void unpackBlock(byte[] bytes, int off) {
        int index = off;

        C0 = (bytes[index++] & 0xff);
        C0 |= (bytes[index++] & 0xff) << 8;
        C0 |= (bytes[index++] & 0xff) << 16;
        C0 |= bytes[index++] << 24;

        C1 = (bytes[index++] & 0xff);
        C1 |= (bytes[index++] & 0xff) << 8;
        C1 |= (bytes[index++] & 0xff) << 16;
        C1 |= bytes[index++] << 24;

        C2 = (bytes[index++] & 0xff);
        C2 |= (bytes[index++] & 0xff) << 8;
        C2 |= (bytes[index++] & 0xff) << 16;
        C2 |= bytes[index++] << 24;

        C3 = (bytes[index++] & 0xff);
        C3 |= (bytes[index++] & 0xff) << 8;
        C3 |= (bytes[index++] & 0xff) << 16;
        C3 |= bytes[index++] << 24;
    }

    private final void packBlock(byte[] bytes, int off) {
        int index = off;

        bytes[index++] = (byte) C0;
        bytes[index++] = (byte) (C0 >> 8);
        bytes[index++] = (byte) (C0 >> 16);
        bytes[index++] = (byte) (C0 >> 24);

        bytes[index++] = (byte) C1;
        bytes[index++] = (byte) (C1 >> 8);
        bytes[index++] = (byte) (C1 >> 16);
        bytes[index++] = (byte) (C1 >> 24);

        bytes[index++] = (byte) C2;
        bytes[index++] = (byte) (C2 >> 8);
        bytes[index++] = (byte) (C2 >> 16);
        bytes[index++] = (byte) (C2 >> 24);

        bytes[index++] = (byte) C3;
        bytes[index++] = (byte) (C3 >> 8);
        bytes[index++] = (byte) (C3 >> 16);
        bytes[index++] = (byte) (C3 >> 24);
    }

    private final void encryptBlock(int[][] KW) {
        int r, r0, r1, r2, r3;

        C0 ^= KW[0][0];
        C1 ^= KW[0][1];
        C2 ^= KW[0][2];
        C3 ^= KW[0][3];

        for (r = 1; r < ROUNDS - 1;) {
            r0 = T0[C0 & 255] ^ shift(T0[(C1 >> 8) & 255], 24) ^ shift(T0[(C2 >> 16) & 255], 16) ^ shift(T0[(C3 >> 24) & 255], 8) ^ KW[r][0];
            r1 = T0[C1 & 255] ^ shift(T0[(C2 >> 8) & 255], 24) ^ shift(T0[(C3 >> 16) & 255], 16) ^ shift(T0[(C0 >> 24) & 255], 8) ^ KW[r][1];
            r2 = T0[C2 & 255] ^ shift(T0[(C3 >> 8) & 255], 24) ^ shift(T0[(C0 >> 16) & 255], 16) ^ shift(T0[(C1 >> 24) & 255], 8) ^ KW[r][2];
            r3 = T0[C3 & 255] ^ shift(T0[(C0 >> 8) & 255], 24) ^ shift(T0[(C1 >> 16) & 255], 16) ^ shift(T0[(C2 >> 24) & 255], 8) ^ KW[r++][3];
            C0 = T0[r0 & 255] ^ shift(T0[(r1 >> 8) & 255], 24) ^ shift(T0[(r2 >> 16) & 255], 16) ^ shift(T0[(r3 >> 24) & 255], 8) ^ KW[r][0];
            C1 = T0[r1 & 255] ^ shift(T0[(r2 >> 8) & 255], 24) ^ shift(T0[(r3 >> 16) & 255], 16) ^ shift(T0[(r0 >> 24) & 255], 8) ^ KW[r][1];
            C2 = T0[r2 & 255] ^ shift(T0[(r3 >> 8) & 255], 24) ^ shift(T0[(r0 >> 16) & 255], 16) ^ shift(T0[(r1 >> 24) & 255], 8) ^ KW[r][2];
            C3 = T0[r3 & 255] ^ shift(T0[(r0 >> 8) & 255], 24) ^ shift(T0[(r1 >> 16) & 255], 16) ^ shift(T0[(r2 >> 24) & 255], 8) ^ KW[r++][3];
        }

        r0 = T0[C0 & 255] ^ shift(T0[(C1 >> 8) & 255], 24) ^ shift(T0[(C2 >> 16) & 255], 16) ^ shift(T0[(C3 >> 24) & 255], 8) ^ KW[r][0];
        r1 = T0[C1 & 255] ^ shift(T0[(C2 >> 8) & 255], 24) ^ shift(T0[(C3 >> 16) & 255], 16) ^ shift(T0[(C0 >> 24) & 255], 8) ^ KW[r][1];
        r2 = T0[C2 & 255] ^ shift(T0[(C3 >> 8) & 255], 24) ^ shift(T0[(C0 >> 16) & 255], 16) ^ shift(T0[(C1 >> 24) & 255], 8) ^ KW[r][2];
        r3 = T0[C3 & 255] ^ shift(T0[(C0 >> 8) & 255], 24) ^ shift(T0[(C1 >> 16) & 255], 16) ^ shift(T0[(C2 >> 24) & 255], 8) ^ KW[r++][3];

        // the final round's table is a simple function of S so we don't use a whole other four tables for it

        C0 = (S[r0 & 255] & 255) ^ ((S[(r1 >> 8) & 255] & 255) << 8) ^ ((S[(r2 >> 16) & 255] & 255) << 16) ^ (S[(r3 >> 24) & 255] << 24) ^ KW[r][0];
        C1 = (S[r1 & 255] & 255) ^ ((S[(r2 >> 8) & 255] & 255) << 8) ^ ((S[(r3 >> 16) & 255] & 255) << 16) ^ (S[(r0 >> 24) & 255] << 24) ^ KW[r][1];
        C2 = (S[r2 & 255] & 255) ^ ((S[(r3 >> 8) & 255] & 255) << 8) ^ ((S[(r0 >> 16) & 255] & 255) << 16) ^ (S[(r1 >> 24) & 255] << 24) ^ KW[r][2];
        C3 = (S[r3 & 255] & 255) ^ ((S[(r0 >> 8) & 255] & 255) << 8) ^ ((S[(r1 >> 16) & 255] & 255) << 16) ^ (S[(r2 >> 24) & 255] << 24) ^ KW[r][3];

    }

    private final void decryptBlock(int[][] KW) {
        int r, r0, r1, r2, r3;

        C0 ^= KW[ROUNDS][0];
        C1 ^= KW[ROUNDS][1];
        C2 ^= KW[ROUNDS][2];
        C3 ^= KW[ROUNDS][3];

        for (r = ROUNDS - 1; r > 1;) {
            r0 = Tinv0[C0 & 255] ^ shift(Tinv0[(C3 >> 8) & 255], 24) ^ shift(Tinv0[(C2 >> 16) & 255], 16) ^ shift(Tinv0[(C1 >> 24) & 255], 8) ^ KW[r][0];
            r1 = Tinv0[C1 & 255] ^ shift(Tinv0[(C0 >> 8) & 255], 24) ^ shift(Tinv0[(C3 >> 16) & 255], 16) ^ shift(Tinv0[(C2 >> 24) & 255], 8) ^ KW[r][1];
            r2 = Tinv0[C2 & 255] ^ shift(Tinv0[(C1 >> 8) & 255], 24) ^ shift(Tinv0[(C0 >> 16) & 255], 16) ^ shift(Tinv0[(C3 >> 24) & 255], 8) ^ KW[r][2];
            r3 = Tinv0[C3 & 255] ^ shift(Tinv0[(C2 >> 8) & 255], 24) ^ shift(Tinv0[(C1 >> 16) & 255], 16) ^ shift(Tinv0[(C0 >> 24) & 255], 8) ^ KW[r--][3];
            C0 = Tinv0[r0 & 255] ^ shift(Tinv0[(r3 >> 8) & 255], 24) ^ shift(Tinv0[(r2 >> 16) & 255], 16) ^ shift(Tinv0[(r1 >> 24) & 255], 8) ^ KW[r][0];
            C1 = Tinv0[r1 & 255] ^ shift(Tinv0[(r0 >> 8) & 255], 24) ^ shift(Tinv0[(r3 >> 16) & 255], 16) ^ shift(Tinv0[(r2 >> 24) & 255], 8) ^ KW[r][1];
            C2 = Tinv0[r2 & 255] ^ shift(Tinv0[(r1 >> 8) & 255], 24) ^ shift(Tinv0[(r0 >> 16) & 255], 16) ^ shift(Tinv0[(r3 >> 24) & 255], 8) ^ KW[r][2];
            C3 = Tinv0[r3 & 255] ^ shift(Tinv0[(r2 >> 8) & 255], 24) ^ shift(Tinv0[(r1 >> 16) & 255], 16) ^ shift(Tinv0[(r0 >> 24) & 255], 8) ^ KW[r--][3];
        }

        r0 = Tinv0[C0 & 255] ^ shift(Tinv0[(C3 >> 8) & 255], 24) ^ shift(Tinv0[(C2 >> 16) & 255], 16) ^ shift(Tinv0[(C1 >> 24) & 255], 8) ^ KW[r][0];
        r1 = Tinv0[C1 & 255] ^ shift(Tinv0[(C0 >> 8) & 255], 24) ^ shift(Tinv0[(C3 >> 16) & 255], 16) ^ shift(Tinv0[(C2 >> 24) & 255], 8) ^ KW[r][1];
        r2 = Tinv0[C2 & 255] ^ shift(Tinv0[(C1 >> 8) & 255], 24) ^ shift(Tinv0[(C0 >> 16) & 255], 16) ^ shift(Tinv0[(C3 >> 24) & 255], 8) ^ KW[r][2];
        r3 = Tinv0[C3 & 255] ^ shift(Tinv0[(C2 >> 8) & 255], 24) ^ shift(Tinv0[(C1 >> 16) & 255], 16) ^ shift(Tinv0[(C0 >> 24) & 255], 8) ^ KW[r--][3];

        // the final round's table is a simple function of Si so we don't use a whole other four tables for it

        C0 = (Si[r0 & 255] & 255) ^ ((Si[(r3 >> 8) & 255] & 255) << 8) ^ ((Si[(r2 >> 16) & 255] & 255) << 16) ^ (Si[(r1 >> 24) & 255] << 24) ^ KW[0][0];
        C1 = (Si[r1 & 255] & 255) ^ ((Si[(r0 >> 8) & 255] & 255) << 8) ^ ((Si[(r3 >> 16) & 255] & 255) << 16) ^ (Si[(r2 >> 24) & 255] << 24) ^ KW[0][1];
        C2 = (Si[r2 & 255] & 255) ^ ((Si[(r1 >> 8) & 255] & 255) << 8) ^ ((Si[(r0 >> 16) & 255] & 255) << 16) ^ (Si[(r3 >> 24) & 255] << 24) ^ KW[0][2];
        C3 = (Si[r3 & 255] & 255) ^ ((Si[(r2 >> 8) & 255] & 255) << 8) ^ ((Si[(r1 >> 16) & 255] & 255) << 16) ^ (Si[(r0 >> 24) & 255] << 24) ^ KW[0][3];
    }
}
